The long term goal of this research proposal is to define the clinical usefulness and limitations of right and left ventricular end-systolic pressure-volume (P-V) relations. Accordingly, the hypotheses which constitute the rationale for this research proposal are: 1) Emax and Vo can be calculated in patients using invasive high-fidelity micromanometer right and left ventricular pressure measurements and right and left ventricular volumes from biplane contrast cineangiography and equilibrium radionuclide angiography; 2) a relationship exists between Emax and non-cineangiographic estimates of end-systolic P-V relations of the right and left ventricles; 3) inotropic interventions produce equivalent directional and quantitatively similar changes in Emax and non-cineangiographic end-systolic P-V relations of both ventricles; and 4) Emax and non-cineangiographic estimates of end-systolic P-V relations are useful in patients with right or left ventricular volume overload for predicting the results of operative correction. The following specific studies are designed to answer these hypotheses: 1) the relationship between non-cineangiographic end-systolic pressure (stress)-volume (dimension) relations and volume intercepts obtained from peak or dicrotic notch pulmonary or aortic pressures and absolute right and left ventricular end-systolic volumes by equilibrium radionuclide angiography and left ventricular dimensions and wall thickness by M-mode echocardiography will be assessed by comparison to Emax and Vo for the corresponding right and left ventricles obtained from invasive high-fidelity micromanometer pressure recordings and volumes from biplane contrast cineventriculography and radionuclide angiography; 2) the directional and quantitative changes in Emax and Vo and the non-cineangiographic end-systolic P-V relations and volume intercepts will be compared at rest and during altered inotropic state using dobutamine or beta-blockade; and 3) the value of right and left ventricular Emax and Vo and the non-cineangiographic end-systolic pressure (stress)-volume (dimension) relations and volume (dimension) intercepts for predicting surgical outcome will be assessed during longitudinal studies in patients undergoing operative correction of their right or left ventricular volume overload lesions. Thus, this research proposal will provide new data regarding the potential clinical usefulness and limitations of end-systolic P-V relations, especially in patients with right or left ventricular volume overload.